1. Technical Field
The present invention relates to optical disc drives in general, and in particular to a method for achieving power savings on an optical disc drive.
2. Description of Related Art
A notebook personal computer (note PC) commonly includes an optical disc drive (ODD). A disc recording medium can be loaded into and unloaded from an ODD. Since the ODD of a note PC is typically used only for reading/writing data from/to a disc recording medium and is not used for other purposes, the period when the ODD is actually operating is extremely short compared with the usage time of the entire note PC. Thus, if electric power is supplied to the ODD even when it is not being used, electric power of approximately 200 mW to 400 mW is unnecessarily consumed internally.
For a note PC, an ODD is usually integrated into a device bay of the note PC by a computer maker. In a tray-loading type ODD, a disc recording medium can be mounted on a tray to be used. An eject switch is mounted in a surface of a housing of the ODD so that when the eject switch is pressed by a user, an eject signal is produced and a tray is slide outward from the housing of the ODD by an electrical driving mechanism such as a motor or a solenoid. When the user momentarily pushes the tray, the tray is drawn inward via the electrical driving mechanism.
An ODD is supplied with an electric power from a power supply circuit of a note PC. The power supply to the ODD may be stopped if it is not expected to be used. In order to use the ODD to which the power supply is stopped by loading a disc recording medium thereto, it is necessary to eject the tray. However, since the tray is electrically operated, it is necessary to pre-apply an electric power to the ODD. It may be possible to eject the tray by a user operating an eject switch after an electric power is supplied to the ODD via a power supply switch or a software program. However, since the provision of a power supply switch may lead to cost increase and may impose an extra operation on the user, the addition of the power supply switch is not very desirable.
For a design in which a power supply to the ODD is maintained, when the user momentarily presses the eject switch, the ODD recognizes the eject signal and the tray is ejected immediately. Since the user recognizes the timely reaction of the tray with respect to the eject button operation as such, it is desirable that the ejection of the tray in the ODD in which the power supply thereto is stopped is carried out in the same manner as the operation of the eject switch only case. In order to solve such a problem, the eject switch may also be functioned as a switch for supplying an electric power to the ODD. However, the ODD may not recognize the eject signal when the power supply is not input thereto, and at a time when the power supply is input to the ODD, the eject switch may return to its original state so that the eject signal disappears. Therefore, in order to eject the tray, the user may need to press again the eject switch after it is confirmed that the power supply is input to the ODD. In other words, the user needs to perform different operations than those made to an ODD in which the power supply thereto is maintained.